After two days watching tv, this sub really rumble!!! It just feel like more attack even though this usually reserve for higher frequencies. I am not watching any action movie, just tv shows, but I can definitely imagine how much attack it will have in action movies during explosion scenes. One scene where the base sound came on, it shook the house!!!! The Velodyne will never do that. I was not on high volume by any stretch.

Sub even have attack? Like the fast transition even though it's low frequency? I am quite sure I was not hearing things about the footsteps sounded to have more attack even it's not low frequency. I was looking for better base, I did not expect to get better attack......That's new.....in a good way.

One time I was touching the rubber rim of the woofer admiring how pretty it is when all the sudden the sub came alive from the scene, it hit my fingers and startled me. The cone really popped!!! I was not on high volume. No wonder you guys worry about 12" sub is not big enough. Before that, I thought you guys are crazy to want dual sub. This sub already shook the house!!!!....and not even with movies, I was just watching "Criminal Minds"!!! How much action do you expect? the show is mostly talk and no action, you lucky to get a gun shot in the show!!!

I am pretty sure some of you, like me, wonder why different subwoofers sound differently, or why different amplifiers sound differently (to a much lesser degree). Very often the argument is that I hear more from this sub vs I hear less from this sub. But we all know a signal is a signal. It cannot disappear. The more I look into it, the more I think the reason is "coherence". That is, the key is in the small signal buried under the loud signal. With a lesser subs (not due to passive radiator, but just poorly design subwoofer), the small signals are not coherent with loud signals. Therefore it sounds as if there is a lot of background noise. But if the coherence is preserved, then that background noise becomes clear as ambience and we can now recognize the previous thought as background noise is now correlated to the loud signals. That is why all tests we use today fail in terms of the ability to test the coherence of sound when both large and small signals are present. The coherence is more important when reverberation is in the recording and in rooms with reasonable reverberation (that is, not an anechoic room). The reason is the reverberation arrives at different time than the source that it derives from and it is always later. That is, we hear the loud signals first and then try to correlate small signals that arrive later. It is a temporal correlation. When the subwoofer is able to preserve the correlation, all the minute low level sound falls into the right place. Without the correlation, the low level sound will be like annoying background noise that you wish to get rid of. In fact we don't have to play the subwoofer loud to destroy the temporal correlation. That means the harmonic distortion figures we normally look at have little (corelation) to the temporal correlation issue.

It makes sense, I discovered my Velodyne is a base reflex, it has a passive radiator at the bottom. My experience is those always give sloppy base, just a long rumble note instead of clean defined notes. It's the fast transition that give the realistic sound. Like the footsteps.

In the field of eletrical engineering, we have synchronous circuit and asynchronous circuit. In synchronous circuit, we have a repetitive clock to simplify timing issue. It is the asynchronous circuit that is more challenging because the event can arrive at any time instance and it has to work regardless the signal arriving sequence. Similarly the footstep does not have harmonic content per se. It requires a particular sequence of energy arrival time to make our brain correlate to the footstep sound we heard in the past.

I've noticed something peculiar about the impact of the sw trim setting on my Yamaha AVR on the SQ of my LV12R.

Let me start by saying I don't crank things past -30MV and actual do some listening in the -40MV range. Also, my Yamaha AVR is known for not having a lot of voltage output from the sub pre-out.

So, what I've noticed is that if I set sub gain knob on LV12R so that YPAO sets sw trim at +6dB, then the sub sounds different than if I set sw gain so that YPAO sets sw trim at 0dB. Keep in mind that in my case YPAO is already setting the subwoofer 6dB or so hot, so I don't crank up sub trim further post YPAO.

As to the different SQ from my sub at +6.0dB sw trim on the AVR, it sounds harder, punchier, stronger, more obvious/in your face.

At 0.0dB trim on the AVR, it has a softer texture and is more laid back sounding. Basically, a sound which is more subtle and mild mannered.

Now considering that these observations are with the MV at very modest volumes and the fact the actual bass level and frequency response is identical between the two combinations of sw gain and sw trim, I'm not sure the difference I'm hearing with a +6.0dB sw trim is due to the sub pre-out clipping or otherwise distorting. If anything, due to the low voltage coming from this pre-out and the use of a MiniDSP 2x4 unbalanced, I think the more aggressive sound might be due to a higher signal to noise ratio.

Any ideas as to why running the sw trim at +6dB sounds more obvious than 0dB sw trim? I noticed similar behavior between -6dB sw trim and 0dB sw trim too, but not necessarily as dramatic of a difference.

Room EQ is a very complicated software. The process involves reading the raw frequency response, then determine the 0db level and then attentuate the peak above the 0db level. In the presence of noise in measurement, you can imagine the 0db level can be slightly off between 0db trim and +6db trim and therefore give you different EQ result. The consistency of giving same EQ result regardless of our initial sub trim is a basic goal of any software. So the only other variable is the noise in measurement. How can this happen? Software algorithm is like walking through a big decision tree. At each branching point, the noise in the measurement can lead to a different decision and therefore has a slightly different outcome.

so i pulled the trigger early on my fv15hp while i finish building my media room downstairs. i currently use it in a temporary room i have setup and the intention was always to buy another when i get the media-room finished. however now with the new offerings, would i gain anything by grabbing an 18 or am i better off buying a matching 15 and then (possibly/probably) adding some 18's into the mix?

I am pretty sure some of you, like me, wonder why different subwoofers sound differently, or why different amplifiers sound differently (to a much lesser degree). Very often the argument is that I hear more from this sub vs I hear less from this sub. But we all know a signal is a signal. It cannot disappear. The more I look into it, the more I think the reason is "coherence". That is, the key is in the small signal buried under the loud signal. With a lesser subs (not due to passive radiator, but just poorly design subwoofer), the small signals are not coherent with loud signals. Therefore it sounds as if there is a lot of background noise. But if the coherence is preserved, then that background noise becomes clear as ambience and we can now recognize the previous thought as background noise is now correlated to the loud signals. That is why all tests we use today fail in terms of the ability to test the coherence of sound when both large and small signals are present. The coherence is more important when reverberation is in the recording and in rooms with reasonable reverberation (that is, not an anechoic room). The reason is the reverberation arrives at different time than the source that it derives from and it is always later. That is, we hear the loud signals first and then try to correlate small signals that arrive later. It is a temporal correlation. When the subwoofer is able to preserve the correlation, all the minute low level sound falls into the right place. Without the correlation, the low level sound will be like annoying background noise that you wish to get rid of. In fact we don't have to play the subwoofer loud to destroy the temporal correlation. That means the harmonic distortion figures we normally look at have little (corelation) to the temporal correlation issue.

Thanks for the detail reply.

Another thing I notice also after almost a week watching TV, maybe is the result I spend more time with your instruction in adjusting. I swear the human voice becomes clearer. Before, there were more base in the human voice that make it a little unnatural, and also make it a little harder to hear the words. Now, it's cleaner and clearer, more separation. Maybe it's also what you describe about the corelation. It is nice and these are not what I expect when I buy this.

I hope you keep the F12SE in production for a while. I have to spend money on other part of the system and I won't get to sub again any time soon. But eventually, I would buy the second one.......not just to have dual sub, more for decoration!!! I am using this as the end table on one side of the sofa. Looks like the glass top is going to cost me like $300. It will look very nice to have a pair one on each side. Sound wise, I am happy with one already.

Ha ha, I cannot stress enough, if you make your big boss like how it looks, it goes a long long way to justify spending more money!!!! Remember, the big boss is going to give you performance review any time, any day of the year, not just once a year!!!

I've noticed something peculiar about the impact of the sw trim setting on my Yamaha AVR on the SQ of my LV12R.

Let me start by saying I don't crank things past -30MV and actual do some listening in the -40MV range. Also, my Yamaha AVR is known for not having a lot of voltage output from the sub pre-out.

So, what I've noticed is that if I set sub gain knob on LV12R so that YPAO sets sw trim at +6dB, then the sub sounds different than if I set sw gain so that YPAO sets sw trim at 0dB. Keep in mind that in my case YPAO is already setting the subwoofer 6dB or so hot, so I don't crank up sub trim further post YPAO.

As to the different SQ from my sub at +6.0dB sw trim on the AVR, it sounds harder, punchier, stronger, more obvious/in your face.

At 0.0dB trim on the AVR, it has a softer texture and is more laid back sounding. Basically, a sound which is more subtle and mild mannered.

Now considering that these observations are with the MV at very modest volumes and the fact the actual bass level and frequency response is identical between the two combinations of sw gain and sw trim, I'm not sure the difference I'm hearing with a +6.0dB sw trim is due to the sub pre-out clipping or otherwise distorting. If anything, due to the low voltage coming from this pre-out and the use of a MiniDSP 2x4 unbalanced, I think the more aggressive sound might be due to a higher signal to noise ratio.

Any ideas as to why running the sw trim at +6dB sounds more obvious than 0dB sw trim? I noticed similar behavior between -6dB sw trim and 0dB sw trim too, but not necessarily as dramatic of a difference.

Room EQ is a very complicated software. The process involves reading the raw frequency response, then determine the 0db level and then attentuate the peak above the 0db level. In the presence of noise in measurement, you can imagine the 0db level can be slightly off between 0db trim and +6db trim and therefore give you different EQ result. The consistency of giving same EQ result regardless of our initial sub trim is a basic goal of any software. So the only other variable is the noise in measurement. How can this happen? Software algorithm is like walking through a big decision tree. At each branching point, the noise in the measurement can lead to a different decision and therefore has a slightly different outcome.

Thanks, does this still hold true when the auto PEQ is disabled post YPAO?

For FV25 I have also tried 2 port mode which pushes the port tuning frequency to 10hz. It improves the music sound more obviously. The bass line becomes just more detailed. The arias in the opera house scene of MI5 (rogue nation) just gives me goose bumps.

How does the 10hz tune change the output at 10hz and 12hz compared to the 3 port tune?

FV18 will be 2db higher output than FV15HP. More improvement is from below 18hz where port output is significant. The improvement is via port compression reduction in the following way. In data-bass test data, our compression is the lowest because the servo feedback adjust the amp output so the output of woofer cone always maintain the consistent frequency response. The only exception is below 18hz where port output becomes significant. Since there is no sensor on ports, compression data show the loss of output even after we maintain correct woofer cone movement. Our observation from the data is 1db additional compression loss for every 5db SPL increase until eventually the port wind noise takes over. So I expect to gain 1db more output just from lower port compression. So overall, it is 2db more output.

For FV25, we expect 6db more output above 30hz. The enclosure size is reduced by 30% per driver, but we have 50% more power from amp. So in the end each driver in FV25 has approximately same output as FV15HP in the baseline comparison. But the number of ports (and port area) increases from 1 to 1.5 (per driver), therefore it cuts down the compression loss slightly.

One interesting information of FV15HP by data-bass is the 12.5hz max output from FV15HP in 1 port mode is not limited by the 2nd order or 3rd order harmonic distortion like in other tests. This means the amp output is not the limiting factor. Instead it is the upper band noise which is caused by port noise. So how can be reduce that upper band noise and allow for a higher output number with 2nd or 3rd order distortion becoming the limiting factor? First, 50% more port area per driver does help and second, we will use a bit more internal sound absorbing material. So that can give us up to 3db output improvement (or up to 9db total output as I referred early in this thread) at 12.5hz point.

For FV25 I have also tried 2 port mode which pushes the port tuning frequency to 10hz. It improves the music sound more obviously. The bass line becomes just more detailed. The arias in the opera house scene of MI5 (rogue nation) just gives me goose bumps.

Could you break this down into a simpler explanation? what is the 12-25hz gains and 30-80hz gains of the FV18 and FV25 over the FV15? Thanks

1799.00 shipped for the FV18 really has my interest peaked at the moment.

It wont...probably take almost 2 FV25's to equal a 4000ulf. The 4000 is absolutely massive.

Yah I have been following the new JTR 4K stats religiously... I may have to jump ship Only problem is I can only afford one after selling the Rythmiks. I will probably wait a while, I am in no way unhappy with these babies. Just chasing that ULF dragon that the Rythmiks are just out of reach for. 75% of the popular ULF demo scenes make both my FV15HPs chuff and 'squeak'.

Yah I have been following the new JTR 4K stats religiously... I may have to jump ship Only problem is I can only afford one after selling the Rythmiks. I will probably wait a while, I am in no way unhappy with these babies. Just chasing that ULF dragon that the Rythmiks are just out of reach for. 75% of the popular ULF demo scenes make both my FV15HPs chuff and 'squeak'.

I am sure dual FV25's would be more then enough to net reference level capabilities into the 10hz range in all but the largest rooms. also being smaller then the Cap4000, should offer more placement options.

I am sure dual FV25's would be more then enough to net reference level capabilities into the 10hz range in all but the largest rooms. also being smaller then the Cap4000, should offer more placement options.

Yah I'm gonna have to go ahead and ask you to give me LESS options, not more. That'd be greeeeat.

Yah I have been following the new JTR 4K stats religiously... I may have to jump ship Only problem is I can only afford one after selling the Rythmiks. I will probably wait a while, I am in no way unhappy with these babies. Just chasing that ULF dragon that the Rythmiks are just out of reach for. 75% of the popular ULF demo scenes make both my FV15HPs chuff and 'squeak'.

the cap4k is in a different league (imo). however the value from the fv15hp is incredible. i'm sure the new offerings from rythmik will also be amazing, but sometimes there's just no replacement for true displacement. personally can't wait to see data-bass get their hands on the new rythmik boxes to see how they stack up against reigning jtr king.

Yah I have been following the new JTR 4K stats religiously... I may have to jump ship Only problem is I can only afford one after selling the Rythmiks. I will probably wait a while, I am in no way unhappy with these babies. Just chasing that ULF dragon that the Rythmiks are just out of reach for. 75% of the popular ULF demo scenes make both my FV15HPs chuff and 'squeak'.

the cap4k is in a different league (imo). however the value from the fv15hp is incredible. i'm sure the new offerings from rythmik will also be amazing, but sometimes there's just no replacement for true displacement. personally can't wait to see data-bass get their hands on the new rythmik boxes to see how they stack up against reigning jtr king.

I actually have a sneaking suspicion the new Rythmiks and the new SVS pb-16 Ultra will rival the JTR.

Are you guys mainly talking about the power output or you talk also about the sound quality that Rythmik is not in the same league?

That is Say if you use 4 of the big Rythmik( two in parallel for each side), are you going to get the same quality base as the expensive one?

Seems like you guys more interested in shaking the house or breaking glass than the sound!!! To me, my definition of a high end system is to be able to sound good at low volume. Even cheap system sounds much better when you crank it up. Case in point if you are old enough to be around in the disco era. You go to the disco and when they crank it up, it really sounded good. I had times I was there too early before the dancing started. They play music at normal level, the system sounded awful!!! But then they cranked it up, it's a different system. Since I have the JM LAB 913.1, I don't have to crank it up, I can get sound stage and transparency at relative low level that won't disturb my big boss sleeping right over the living room.

That's another reason I took down the surround sound was it was fun having the sound flying around, housing shaking explosion.........But it's tiring watch tv like this hours a day every day!!! It ended up I did more show and tell to friends when they visit than to actually enjoying it. I took it down. Those surround sound lost the sound stage and transparency to me. Things don't fly around if you have it on low volume. My simple system sounds big even though it's stereo, it has the hall effect that like in a big room and you can hear the 3D effect. It's just a lot more natural to me. Maybe I am a crazy odd ball.

My next project is eyeing on a better pair of speakers. I've been looking on ebay as it's too much to buy new and I am not willing to pay $10K for a pair of speakers. I'll let someone depreciate for me.

One thing attract me to Rythmik is you can't find on ebay used. I saw only one for $900 used!!! To me it's a good sign, people are holding on to theirs. I was looking at Martin Logan and B&W speakers, but they have so so many on ebay!!! Why are people getting rid of them? That bugs me.

How does the 10hz tune change the output at 10hz and 12hz compared to the 3 port tune?

In fact, you will be surprised to know the outputs at 10hz under 2ports and under 3ports are the same. Here is the reason. In 3port mode, 10hz is below 12.5hz by a factor of sqrt(2/3). The woofer output is twice of port output. But because the woofer output and port output are out of phase below tuning frequency, the net is same magnitude as port output. At 2 port mode and 10hz, the woofer almost has no output, but the port output at 10hz is coincidentally same in magnitude as in 3 port mode. Therefore the output remains the same at 10hz for both 2 ports and 3 ports modes. The difference is 2 port modes will have less ringing and less phase shift and therefore more like a sealed sub.

PS: With 3 ports at 10hz, one can see large excursion from woofers and yet its output is partially negated by the out-of-phase port output. On the other hand with 2 ports at 10hz, the woofer cone moves much less and all output is from ports. This is because with 2ports (3 ports), the woofer output and port output are always in-phase above 10hz (12.5hz)